1. Field of the Invention
The present invention relates to a wireless Local Area Network (LAN) system. More particularly, the present invention relates to a cryptographic method using dual encryption keys and a wireless Local Area Network (LAN) system therefor that is capable of increasing security by encoding data using dual encryption keys consisting of first and second group keys in an ad-hoc network.
2. Description of the Related Art
Generally, a wireless Local Area Network (LAN) system includes an ad-hoc network where a plurality of terminals, each of which includes a wireless Network Interface Card (NIC), are connected to each other and independently to wired LANs, and an infrastructure network where wireless terminals are connected to wired LANs through wireless access nodes having a wireless NIC. An ad-hoc network consists of two or more wireless terminals. Contrary to the infrastructure network, the ad-hoc network does not have a fixed wireless access node for accessing other wireless terminals. If the respective wireless terminals of an ad-hoc network exist within a distance that allows communication between the terminals, the respective wireless terminals are recognized by each other as belonging to the same ad-hoc group by setting the same service set identifiers (SSIDs). If one wireless terminal is connected to the Internet, that wireless terminal is used as a server and the other wireless terminals within the same ad-hoc group share access to the Internet through that server using any sharing program of the Internet or any sharing menu of Microsoft Windows®.
Generally, an ad-hoc network is formed by specific users having a common interest. Since most information in the ad-hoc group is intended to be private, and that information is temporarily generated for specific purposes, the information does not have continuity. In addition, in an ad-hoc network, the creator of a group becomes a temporary group master and participants of the group are allowed participation permission in the group with only minimal information.
In a wireless LAN system of an ad-hoc network, transmission data is encoded, for communication security, to provide confidentiality and integrity of data. Due to the characteristics of an ad-hoc network, a cryptographic method using symmetric keys is primarily used. FIG. 1 illustrates a schematic view of a conventional cryptographic method in a wireless LAN system of an ad-hoc network.
As shown in FIG. 1, in a system using symmetric keys, all wireless terminals 11, 13, 15, 17, and 19, which constitute an ad-hoc network 10, share a group key value, wherein the group key value is set by the users. That is, all users in the ad-hoc group must know the group key value in advance of transmitting data, which causes some inconvenience. Further, although the users know the group key value in advance, the group key value must often be modified to minimize exposure of the group key value to hacking by a malicious user. Therefore, the group key value must be frequently created, distributed, and modified. However, since no apparatus provides such a function in a current ad-hoc network, the high possibility of being hacked by a malicious user poses a serious threat.